Best Places (UK) for Theoretical Physics

As it happens, I've already applied to a couple of universities but I think it would definitely be a good idea to apply to a few more in order to improve my chances of being accepted somewhere.

I would like to ask you what you think the best places in the UK are to do a Theoretical Physics PhD (specifically I would like to do research involving General Relativity/Quantum Field Theory/String Theory/Black Holes/Quantum Gravity - any of this kind of stuff).

I'm not going to list the places I have already applied as I don't want to influence you in any way whatsoever!